The importance of error free classification of a patient's blood and a donor's blood when the latter is to be transfused to the patient is so well understood by those working in the field of blood banking that it need not be reiterated here other than to say that transfusion of incompatible blood to a patient can lead to severe hemolytic reactions and even to the death of the patient. This incompatibility arises from the fact that red blood cells vary in their structure by what are called antigens so that one person's blood cells may have certain antigens that differ from those carried by the red blood cells of another person. If foreign antigens are introduced into a person's blood stream, his immunological system immediately produces antibodies that destroy the foreign material, i.e., the introduced blood cells carrying the foreign antigen. The incompatibility may also arise from the donor's serum which may contain antibodies that would destroy the patient's red blood cells because of the antigens carried thereon. Therefore, every effort must be made to facilitate the proper classification of blood and to properly and positively identify the classified blood so that incompatible blood transfusions are avoided.
The principal blood cell antigens are designated A and B, with some cells having A antigens, some having B antigens, some having both A and B antigens, and some having neither A nor B antigens. Thus, blood having red cells carrying A antigens is referred to as Type A blood, that having cells carrying B antigens as Type B blood, that having cells carrying both A and B antigens as Type AB blood, and that having cells which do not carry either antigen as Type O blood. Other antigens are important, such as the D and other Rh antigens. The ABO blood group is generally determined by a forward typing protocol in which a person's red cells are mixed with antiserum reagents containing known antibodies to see if agglutination takes place. Thus, red cells are mixed with anti-A serum, anti-B serum, anti-AB serum, and anti-D serum. If the mixture of anti-A serum and the patient's red cells agglutinate and the mixture of anti-B serum and red cells does not, the patient's blood group is Type A. That is, the patient's red cells carry the A antigen. If the reverse result obtains, then the patient' s blood group is Type B. In both of these instances, the anti-AB mixture would agglutinate. If agglutination occurs in both mixtures, and in the anti-AB mixture, the blood group is Type AB, and if agglutination is absent in all mixtures, the blood group is Type O. If the D antigen is present, i.e., the anti-D serum-cell mixture agglutinates, the blood group is positive, e.g., Type A+, and if the D antigen is absent (when the mixture does not agglutinate) the blood group is negative, e.g., Type B-.
It is so important to make a correct determination of a person's blood type when a blood transfusion is contemplated, or may become necessary, that a double check called reverse typing is ordinarily made in the typing procedure. Thus, in addition to observing if there is an agglutination reaction when the person's red cells are mixed with antibody reagents such as anti-A serum, the person's serum is mixed with standard red cell reagents having A antigens and B antigens. If the serum tests positively, i.e., agglutinates, with the A antigen red cells and negatively with the B antigen red cells, then the person's blood group is Type B. If the reverse result is observed, then the person's blood group is Type A, and if the results of both tests are negative, the blood group is Type AB. If both tests are positive, the blood group is Type O.
In general, the foregoing blood groups offer a satisfactory preliminary categorization of blood types, but there are other factors, i.e., other antigens, which are atypical and have to be taken into account to assure, essentially, absolute compatibility between a patient's blood and that of a donor which is to be transfused to the patient. Therefore, still other tests are conducted to determine whether or not a person's serum contains antibodies that would destroy red cells that carry antigens that are less frequently encountered but which may be carried by a donor's red cells. In carrying out these other tests, a person's serum is mixed with reagent red cells to determine whether or not agglutination occurs. There may, in fact, be several different reagent red cells, such comprising red cells carrying different groups of antigens. If none of the serum reagent red cells mixtures agglutinate, there is essentially no incompatibility between the person's serum and any of the antigens carried by the reagent blood cells. In other words, the person's serum contains no antibodies that would destroy red cells carrying antigens of the type carried by the reagent red cells. If, on the other hand, agglutination occurs in a serum reagent red cell mixture, still other tests must be performed to determine the particular antibody causing the agglutination. Even after the tests for atypical antibodies are completed and a complete profile of a patient's blood is known, and a tentative assignment of donors' blood (which had undergone the same battery of tests and has a profile similar to that of the patient's blood) is made for the patient, still other tests are performed to determine if the patient's serum agglutinates red cells of the various tentative donors. This other testing is referred to as crossmatching, and only if there is no agglutination will a donor's blood be suitable for transfusion to the patient.
It is clear from the foregoing that many separate tests, each using a separate reaction vessel or cuvette, are performed using a person's red cells and serum and that the results of those tests must be recorded and tabulated with great precision to assure the proper classification of a blood type and the association of that data with a particular person. Thus, each individual cuvette must be marked to identify the person whose blood is being tested and the reagent that is added to the cuvette so that each separate test result can be recorded for the person. In this connection, it is noted that clerical mistakes are generally conceded to be the single largest cause of errors in a blood bank. Transcription and filing errors account for more than 93% of all blood bank errors. See H. F. Taswell and C. L. Sonnenberg, "Blood Bank Errors: A New Functional Classification", Abstracts, American Association of Blood Banks, 1979, page 24.
While the prior art has addressed this problem, see particularly U.S. Pat. No. 3,033,412 which discloses clip means for joining a number of test tubes together, and U.S. Pat. No. 3,905,772 which discloses a unitary group of cuvettes and an indicia member which facilitates forward and reverse typing of blood groups according to the general ABO classifications, it has been found that blood banks, in general, still adhere to their old methods of using individual test tubes or cuvettes which are individually marked with a marking pen to identify the red cell reagent test or serum reagent test that occurs in each cuvette. The cuvettes are also individually marked to identify the donor of the red cells and serum, that is, the person whose blood is being typed and classified.